Aircraft rotor wing construction



Nov. 5, 1946. J. 5. PECKER AIRCRAFT ROTOR WING CONSTRUCTION Original Filed July 17, 1945 3 Sheets-Sheet' 1 .10 SEPH .s; PEc/rsfi',

Nov. 5, 1946.

J. s. PECKER AIRCRAFT ROTOR WING CONSTRUCTION 194:5 '3 Sheets-Sheet 2 Original Filed July 17 i (IIIIIIIIIIIA J'OsEPH s. PEc/rE/i;

. Nov. 5', 1946. .1. s. PECKER' AIRCRAFT ROTOR WING CONSTRUCTION Original Filed Jul 17, 1945 s Sheets-Sheet s vase/ 11 6.PEc/fE/?,

Patented Nov. 5, i946 'Mlhttt UNlTED STATES PATENT OFFICE Original application July 17, 1943, Serial No.

495,197. Divided and this application December 31, 1943, Serial No. 516,476

(Cl. 244-l23) 16 Claims. 1

This invention relates to the construction of a rotor wing for aircraft such as used on helicopters and autogyros, and the construction may be found to be adapted for use in other wing surfaces and/or control surfaces of aircraft, although it is particularly adapted for rotor wing construc tion for aircraft.

An object of the invention is the provision of a plurality of blades which comprise the rotor wing, of plywood or other non-metallic material, although the construction of some or all of the parts of the blade of metallic material is not excluded. Where plywood is used the grain direc,

tion of the several plies would be at angles to each other.

Another object of the invention is to provide an aircraft rotor wing construction of plywood or similar material which is of semi-rigid construction, and which is so braced whereby to secure utmost strength for weight, particularly in the direction of the component of centrifugal forces applied to the rotor blade during rotation.

A further object of the invention is to provide a rotor wing comprising a plurality of blades, each of which is cellular in form with the walls of the cells and the lengthwise dimension of all cell forming members disposed longitudinally of the rotor blade.

An additional object of the invention is to provide a rotor wing the blades of which are of hollow construction, and whereby great strength for weight is secured by the provision of longitudinal extending tension members and box spars.

Additional objects will be found hereinafter throughout the specification, reference being had to the accompanying drawings.

In the drawings:

Figure 1 is a View in perspective, of an aircraft of the type to which the rotor wing construction of this invention is particularly adapted;

Figure 2 is a view in perspective, and partly broken away, of a preferred form of this invention;

Figure 3 is a section of the wing tip taken substantially on the line 3-.-3 of Figure 2;

Figure 4 is an enlarged section taken substanrows the grain direction in the veneer of the respective plies thereof;

Figure 8 is an enlarged fragmentary section taken at the portion 88 of Figure 5;

Figure 9 is a plan view of the wing shown in Figure 2 partly broken away to illustrate the approximate extent of the metal spar and surrounding molded box spar;

Figure 10 is an enlarged longitudinal section taken substantially on the line l0-l c of Figure 9, and broken away for clearness of disclosure;

Figure 11 is a fragmentary section taken substantially on the line ll-ll of Figure 10, and

Figure 12 is a plane view, partly broken away and partly in section of an adaptation of the wing to jet drive.

Referring to the drawings in detail, the wing construction I5 illustrated in Figure 1 to 5, and 9 to 11, is supported by a metal stub spar 16 extending substantially one-third the wing length.

Coextensive with that portion of the spar which extends within the wing is the spar connector sleeve, generally designated ll, by means of which the metal stubvspar I6 is connected with the molded box spar IS. The connector sleeve I1 is preferably crenelated for ultimate strength for weight in torsion and is made up of pairs of angles i9, 20 which form a continuous enclosing sleeve for the stub shaft 16 by reason of having their edges welded together at 2i, Figure 4:.

As shown in Figures 2 and 4, this connector sleeve ll presents two separated, elongated flat surfaces 25 to the inner surface of each wall of the rectangular molded box spar it. These sur faces are secured to the abutting box spar surfaces by bonding, or for instance, by rivets such as 25, Figure 2. In this manner, the connector sleeve ll connects the metal stub spar ill with the overlying or surrounding portion of the molded box spar I8.

This box spar i8, as shown in Figures 2 and 9, is substantially coextensive with the length of the wing tip proper and terminates adjacent the joint between the wing proper and the wing tip. It is hollow throughout and the outer end is closed by the metal end plate 26, Figures 2, 10 and 11. The other end of thebox spar i8 is secured to the connector sleeve [1, as described above, and through the sleeve I! to the metal stub spar it. The inner ends of the connector sleeve H and box spar I8 closely engage the inner surface of the inner end wall 21 of the wing proper.

Extending through suitable apertures provided in the box spar end plate 26 are four tension members 39, 3!, 32 and 33. The outer ends of these tension members are fixedly secured to the end plate 26. The four tension members extend throughout the hollow length of the box spar l8 adjacent its corners and terminate inwardly in screw portions or screw threaded portions 313 provided with nuts 35 by means of which they may be adjusted to stress the box spar l8, and throughthe box spar 18, the entire wing l5.

The bracket 36 has its cylindrical portion 3? fixed to the metal stub spar IS in suitable manner, as by rivets 38, and the flange or foot portion 39 thereof is secured in suitable manner, as by rivets 40, to the inner end wall 21 of the wing proper. Suitable apertures are provided in the flange or foot portion 39 to receive the screw portions or screw threaded portions 34 cf the tension members 30-34.

Thus, the spar structure which forms in effect the backbone of the rotor blade, comprises a metal stub spar extending throughout a minor portion only of the wing length, a crenelated metal connector sleeve surrounding and fixed to the portion of the stub spar within the wing, a laminated tapering box spar extending from the inner end of the wing substantially throughout its length and surrounding and attached to the connector sleeve, and a plurality of tension members, preferably cables, extending throughout the length of the box spar and adjustable in length for pre-stressing and compensating for shrinkage or warping. The stub spar, connector sleeve, tension members are all disposed substantially longitudinally of the rotor blade or wing, as are the walls of the box spar, whereby to secure utmost strength for weight in the direction of components of centrifugal forces applied to the rotor blade during rotation.

The wing structure surrounding the spar structure or backbone, is of cellular form with the walls of the cells and the lengthwise dimension of all cell-forming members disposed longitudinally or axially of the rotor bade. As shown in Figures 2, 4 and 5, the nose stringer or nose piece 4! is laminated with a flat rear surface and curved forward surface, the laminations being transverse.

The first longitudinal cell is designated 42 and is formed by the nose stringer 4 1, vertical stringer or wall 43, and a pair of stringers in the form of angles of substantially U-section designated 44 and 45, with their legs or side flanges bonded respectively to the rear, flat surface of the nose stringer ll and the forward surface of the wall or stringer 43.

The second cell is designated 66 and is formed by the stringer or wall 43, the stringer or wall 47 and a pair of stringers or angles 48 and 59, similar to the above described stringers or angles 44 and 45, and similarly disposed with respect to their cell, i. e., the legs or side angles are bonded respectively t the rear surface of the wall 43 and the forward surface of the wall 4?. The wall 47' closely engages the forward wall of the box spar I8 and is bonded thereto.

A similar wall or vertical'stringer i closely engages the rear wall of the box spar l8, and is bonded thereto in similar manner. The third cell 52 is formed by the aforementioned vertical stringer or wall 5|, a second vertical stringer or wall 53 and a pair of similar oppositely disposed stringers or angles 54 and 55 with their legs or vertical side flanges bonded respectively to the stringers or walls 5| and 53.

The fourth cell is designated 56 and is formed by the aforementioned stringer or wall 53, the

4 vertical stringer 6r wall '57 and a pair of oppd sitely disposed stringers or angles 58 and 59, with their vertical legs or flanges bonded to the vertical stringer or wall 51.

The remaining or rearmost cell to is formed by a stringer or angle 6! and the tailpiece or trailing edge piece or stringer 62. The angle 6! is of substantially triangular section with its leg portions or flange disposed generally horizontally and the intermediate portion arranged vertically, in close contact with the stringer or wall 57, and bonded thereto. As shown in Figures 4 and 5, the forward end of the tail piece 62 is provided with steps for receiving the ends of the flanges of the angle 6| which are bonded therein.

The main skin of the wing is formed in halves, the upper half 63 terminating forwardly adjacent the mid-portion of the curved forward surface of the nose piece or stringer ii, and terminating rearwardly adjacent the mid-portion of the curved outer surface of the tail piece or stringer 82. The lower half 65 of the main skin has its edges in engagement with the edges of the upper half 63. In order to protect the forward seam at the forward junction of the skin halves 63 and 64, and in order to secure free flow of air over the nose portion of the wing, a nose skin, buffer skin, or nose skin covering 55 is provided, which covers the nose portions of the skin halves 63 and 84, and the seam at their junction, and which terminates roughly adjacent the midpoint of the box spar [8 both upwardly and downwardly, as shown in Figures 4 and 5 of the drawings.

Beyond the outer end of the box spar l8 and the end plate 26, secured thereto, are a pair of oppositely disposed oppositely directed stringers or angles, or substantial U-section, designated 66 and 67, with their flanges or legs bonded respectively to the longitudinal stringers or walls 41 and 51.

As shown in Figures 3 and 12, all of the above described stringers or walls and angles terminate just short of the ends of the skin 63, 64. The ends of the skin halves 63 and ti l closely engage the edges of the complementary halves 68 and 69 which form the wing tip. The curved edges of these complementary half skins or tip halves are received in steps provided in the tip edge stringer T6 for this purpose. A substantially annular connector 12 underlies the joint 'H between the skins of the tip and wing proper, which are bonded thereto as shown in Figures 3 and 12.

As shown in Figure 5, apertures l3, l4 and may be provided for supplying hot air injected in suitable manner into the box spar 18 into the forward cells 42 and 46, for de-icing. Where the course of air is omitted, such apertures provide for insulation and venting, so that distortion of the wing in operation occurs without building up of internal pressure. Like apertures 16, ll, l8, l9 and Bil provide, when desired, for ventilation and venting of the cells 52 and 55 and 65.

In the modification illustrated in Figure 6, the spar structure is of the same construction as in the embodiment illustrated in Figures 2 to 5, and 9 and 10. The skin is similar, being formed by the skin halves 63 and 64 covered adjacent the leading edge by the-buffer skin or protective skin 65. The wing tip construction is the same as illustrated in Figures 2 and 12, and is secured to the skin proper 63 and 64 in the same manner. However, the vertical stringers-or walls 53, 41, 5|, 53 and 51, and the angle-s 44, 45, 48, 49, 54, 58, 59 and 6! are omitted and the trailing edge stringer or tail piece 62 is modified as will hereinafter appear.

In the modified structure a plurality of telescopically arranged longitudinal stringers or angles of substantial U-section are substituted for the above enumerated stringers and angles, and perform the function performed thereby. Surrounding the oppositely disposed angles BI and 82 with their flanges abutting substantially at the middle of the upper and lower outer engaged surfaces of the box spar l3, and with the intermediate portions joining the fianges disposed substantially vertically, are a second pair of like, oppositely disposed, angles 83 and 84, which overlap the aforesaid angles 8| and 82, and are bonded thereto, the forward angle 83 having its central portion complementary with and closely surrounding the forward stringer or nose piece 4! to which it is bonded. Rearwardly of the angle 84 is a similar angle 85 of slightly smaller size with its flanges or legs abutting and bonded to the flanges of the angle 85. The trailing edge stringer or tail piece 86 is of reduced size and the outer curved surfaces thereof are surrounded by the rearmost angle 8'! which has its legs or flanges engaging and bonded to the le s or flanges of the angle 85. The half skins 63 and 64 are bonded to the engaged leg portions or flanges of the angles 8i85, 87 in a manner which will be readily understood.

Optionally, the wing structure shown in Figure 6 may be provided with apertures or vents for the purposes enumerated above. These apertures may comprise the apertures 9! in the angle 8! providing communication between the first and second cells, the apertures or vents 92 in the forward vertical wall of the box spar l8 and providing communication between the second cell and the interior of the box spar. The aperture 93 in the rearward vertical wall of the box spar may provide communication between the box spar and the third cell, the apertures 94 in the angle 82 between the third and fourth cells, the apertures 85 in the angle 84 between the fourth and fifth cells, and the apertures 96 in the angle 85 between the fifth and sixth or rearmost cell.

' While the skins, stringer, angles and box spar are capable of production from various molded materials either laminated or otherwise, a preferred material is illustrated in Figures '7 and 8, and comprises three-ply plywood composed of three layers or sheets of veneer bonded together. For ultimate strength the plies are arranged so that the grain direction of the first or outer ply t 88 is substantially 45 degrees from the longitudinal axis of the wing, spars, stringers and skins, the second or intermediate ply 89 has its grain direction substantially parallel with the longitudinal direction of the wing, and the third or inner ply 98 had its grain direction at 45 degrees from the longitudinal direction or axis on an inclination opposite that of the first ply or substantially at a right angle to the grain direction therein.

As shown in Figures 2, 7 and 10, the wood veneer in each layer may comprise narrow strips out in the grain direction with their edges glued or bonded together in a butt-joint to form sheets of substantial width.

While the sheets of three-ply plywood forming the respective skins, stringers, walls and angles have been shown as possessed of substantial thickness, this is an exaggeration made solely in the interest of clearness and conven ence of illustration and disclosure, it being clearly under stood by those skilled in the art that the thickness of the plywood and constituent veneer sheets will vary widely with the strength of the wood. It is also well recognized by those skilled in the art that extremely thin plywood sheets provide strength amply adequate for the purpose here intended, and to withstand the forces and stresses to which they may be subjected.

As shown in Figure 12, the wing constructions illustrated in the drawings and described above, are readily adaptable to jet drive for the rotor wing. When this is found desirable, the box spar end plate S8, Figure 12, is provided with an aperture 99 into which is inserted and rigidly secured, the inner end of an air-pipe ltd, provided at its outer end with a nozzle It! disposed at the desired angle, and supported by a transverse rib Hi2 and angular block 13, provided in the wing tip adjacent its outer end. If desired, the air pipe may be rotatably secured in the box spar end plate 98, and suitable controls of known type provided for rotating the air pipe to vary the angle of the nozzle it! with respect to the wing proper. Compressed air for driving or initiating rotation of the wing may be injected through the metal stub spar, for instance, into the interior of the box spar, whence it flows through air pipe Hit and nozzle H)! to initiate rotation of the wing or drive the wing. In this embodiment, no vents or apertures are provided between the interior of the box spar i8 and the respective Wing cells from which it is sealed off for obvious reasons.

In Figure 1 is illustrated a rotary wing aircraft of a type to which blades or rotor wings constructed according to this invention, are particularly adapted. As shown, the metal stub spars 96 carrying blades or rotor wings iii are rotatably secured in a hub m5, which is rotatably driven by a rotor shaft (not shown), from the engine of the craft (also not shown), which concurrently drives the tail propeller I 96 through which stabilization, guide and control of the craft is mainly secured. Through linkages including rods Hill, the respective stub spars Iii are connected with the swash plate 5%, which, in turn, is manually controlled by the pilot through controls including the control rods m9. Through positional control of the swash plate, the pitch of the respective blades or rotor wings, and the angle of attack or angle of incidence of the rotor wing, are controlled as desired.

The craft illustrated in Figure 1 is a helicopter of the closed fuselage type, comprising a closed fuselage ill with door ill, provided with an openwork boom or tail spar H2 'for supporting the tail propeller H16 in suitable location with respect to the rotor wing or wing system l5, It, lii5it9, and for supporting the tail propeller drive shaft (not shown). It is of course to be understood that the rotor wing constructions herein illustrated, and above described, are as readily adaptable to all types of known rotary wing aircraft, including the free wing or flapping wing type of craft known in the art as Autogiros.

Suitable landing gear for operation on land or water is of course provided, and may comprise the tricycle landing gear shown, which comprises suitable mounted fo-rewheel unit H 3 and side wheel units H5 suitably located for attainment of ultimate stability and security. I

In the specification I have described the skin as being com osed of plywood, but it is to be expressly understood that I may substitute any other skin material, For instance the several layers shown in Figure 8 may be of cloth, which cloth layers may be suitably impregnated with a substance to give them body. 01' I may use one or more layers of plywood with other layers of a different material such as cloth.

This application is a division of my application Serial No. 495,197, filed July 17, 1943, noW Patent It will be understood that the above description and accompanying drawings are for illustrative purposes only, and that I do not desire to be limited in the practice of this invention except as defined by the appended claims.

What is claimed is:

1. In a rotor blade, a skin for said blade consisting of a plurality of laminations, and means for rigidly supporting said skin, said. supporting means including a plurality of cell members extending longitudinally of the axis of said blade, one of said cell members being located substantially centrally of said blade, means for mounting said rotor blade comprising means non-rotatably fixed with relation to said cell member, said means being connected to the interior of said cell member and being co-extensive therewith, said other cell members being located on said opposite sides of said centrally located cell member with at least one of said other cell members rigidly connected at one side of said centrally located cell member.

2. In a rotor blade, a skin for said blade consisting of a plurality of plywood laminations, and means for rigidly supporting said skin, said supporting means including a plurality of cell members extending longitudinally of the axis of said blade, one of said cell members being located substantially centrally of said blade, means for mounting said rotor blade comprising means non-rotatably fixed with relation to said cell member, said means being connected to the interior of said cell member and being co-extensive therewith, said other cell members being located on said opposite sides of said centrally located cell member with at least one of said other cell members rigidly connected at one side of said centrally located cell member.

3. In a rotor blade, a skin for said blade consisting of a plurality of plywood laminations with the grain of at least one of the laminations extending at an angle to the longitudinal axis of said blade, and means for rigidly supporting said skin, said supporting means including a plurality of cell members extending longitudinally of the axis of said blade, one of said cell members being located substantially centrally or said blade, means for mounting said rotor blade comprising means non-rotatably fixed with relation to said cell member, said means being connected to the interior of said cell member and being co-extensive therewith, said other cell members being located on said opposite sides of said centrally located cell member with at least one of said other cell members rigidly connected at one side of said centrally located cell member.

4. In a rotor blade, a skin for said blade consisting of a plurality of plywood lamination with the grain of at least one of the laminations extending at an angle to the longitudinal axis of said blade and at an angle to the grain of another lamination, and means for rigidly supporting said skin, said supporting means including a plurality of cell members extending longitudinally of the axis of said blade, one of said cell members being located substantially centrally of said blade,

means for mounting said rotor blade comprising means non-rotatably fixed with relation to said cell member, said means being connected to the interior of said cell member and being co-extensive therewith, said other cell members being located on said opposite sides of said centrally located cell member with at least one of said other cell members rigidly connected at one side of said centrally located cell member.

5. In a rotor blade, a skin for said blade, said skin consisting of a plurality of plywood laminations with the grain of certain of said laminations extending at substantially right angle to each other and at substantially a 45 degree angle to the longitudinal axis of said blade, and means for rigidly supporting said skin, said supporting means including a plurality of cell members extending longitudinally of the axis of said blade, one of said cell members being located substantially centrally of said blade, means for mounting said rotor blade comprising means non-rotatably fixed with relation to said cell member, said means being connected to the interior of said cell member and bein co-extensive therewith, said other cell members being located on said opposite sides of said centrally located cell member with at least one of said other cell members rigidly connected at one side of said centrally located cell member.

6. In a rotor blade, a skin for said blade, said skin consisting of at least three plywood laminations with the grain of certain of said laminations extending substantially at right angles to each other and at substantially a 45 degree angle to the longitudinal axis of said blade and the grain of a third lamination extending substantially longitudinally of the blade, and means for rigidly supporting said skin, said supporting means including a plurality of cell members extending longitudinally of the axis of said blade, one of said cell members being located substantially centrally of said blade, means for mounting said rotor blade comprising means non-rotatably fixed with relation to said cell member, said means being connected to the interior of said cell member and being co-extensive therewith, said other cell members being located on said opposite sides of said centrally located cell member with at least one of said other cell members rigidly connected at one side of said centrally located cell member.

'7. In a rotor blade, a skin for said blade, said skin consisting of at least three plywood laminations with the grain of certain of said laminations extending substantially at right angles to each other and substantially at a 45 degree angle to the longitudinal axis of theblade and with the grain of a third lamination extending substantially parallel with the longitudinal axis of said blade, said third lamination lying between said 45 degree angle laminations, and means for rigidly supporting said skin, said supporting means including a plurality of cell members extending longitudinally of the axisof said blade, one of said cell members being located substantially centrally of said blade, means for mounting said rotor blade comprising means non-rotatably fixed with relation to said cell member, said means being connected to the interior of said cell member and being co-extensive therewith, said other cell members being located on said opposite sides of said centrally located cell member with at least One of said other cell members rigidly connected at one side of said centrally located cell member. V

8. In a rotor blade, a skin for said blade consisting of a plurality of laminations, and means for rigidly supporting said skin includin a box spar having vertical walls extending longitudinally of said blade and a plurality of pairs of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other and each pair from another pair of angle members, said skin having upper and lower surfaces, the vertical walls of said spar serving to space said surfaces.

9. In a rotor blade, a skin for said blade consisting of a plurality of laminations, nd. me s for rigidly supporting said skin including a box spar having vertical Walls extending longitudinally of said blade and a plurality of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other and each pair from another pair of angle members, said skin having upper and lower surfaces, the vertical walls of said spar serving to space said surfaces, said spar having substantially horizontal surfaces, and means for attaching the same to the said upper and lower surfaces of said skin.

10. In a rotor blade, a box spar extending longitudinally and substantially centrally thereof, a plurality of pairs of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other and each pair from another pair of angle members, several of said pairs of angle members and stringers forming longitudinally extending cells located on opposite sides of said box spar, a nose stringer forming the side wall of one of said'cells, a rearmost cell formed of a three sided member and a trailing edge piece, and a skin comprising upper and lower skin halves bonded to said nose stringer, the upper and lower surfaces of said cells, box spar and trailing edge piece, each skin half comprising a multi-layer plywood section having layers the grain of which extends at angles to each other and to the longitudinal axis of the rotor blade.

11. In a rotor blade, means forming a plurality of cells extending longitudinally of the blade axis, a nose stringer having a rear Wall forming a side of one of said cells the upper and lower walls of said last named cell having side flanges which lie against the rear wall of said nose stringer, a skin, means attaching said skin to the upper and lower surfaces of said cells, and to said nose stringer, said skin being composed of a bonded multi-layered plywood.

12. In a rotor blade, a. box spar extending 1ongitudinally and substantially centrally thereof, a plurality of pairs of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other and each pair from another pair of angle members, several of said pairs of angle members and stringers forming longitudinally extending cells located on opposite sides of said box spar, a nose stringer forming the side wall of one of said cells, a rearmost cell formed of a three sided member and a trailing edge piece, and a skin comprising upper and lower skin halves bonded to said nose stringer, the upper and lower surfaces of said cells, box spar and trailing edge piece.

13. In a rotor blade, a box spar extending longitudinally and substantially centrally thereof, a plurality of pairs of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other, the sides of said box spar, angle members and stringers being composed of multi-layered plywood construction and bonded to each other.

14. In a rotor blade, a boX spar extending longitudinally and substantially centrally thereof, a plurality of pairs of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other and each pair from another pair of angle members, several of said pairs of angle members and stringers forming longitudinally extending cells located on opposite sides of said box spar.

15. In a rotor blade, a box spar extending longitudinally and substantially centrally thereof, a plurality of pairs of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other and each pair from another pair of angle members, several of said pairs of angle members and stringers forming longitudinally extending cells located on opposite sides of said box spar, and a nose stringer forming the side wall of one of said cells.

16. In a rotor blade, a box spar extending longitudinally and substantially centrally thereof, a plurality of pairs of angle members of U-section, longitudinal stringers separating the angle members of each pair from each other and each pair from another pair of angle members, several of said pairs of angle members and stringers forming longitudinally extending cells located on opposite sides of said box spar, a nose stringer forming the sidewall of one of said cells, and a rearmost cell formed of a three sided member and a trailing edge piece.

JOSEPH S. PECKER. 

